In the presented practice-oriented probabilistic approach for the seismic performance assessment of building structures, the SAC-FEMA method, which is a part of the broader PEER probabilistic framework and permits probability assessment in closed form, is combined with the pushover-based N2 method. The most demanding part of the PEER probabilistic framework, i.e. Incremental Dynamic Analysis (IDA), is replaced by the much simpler N2 method which requires considerably less input data and much less computational time, but which can, nevertheless, often provide acceptable estimates for the mean values of the structural response. Using some additional simplifying assumptions that are consistent with seismic code procedures, an explicit equation for a quick estimation of the annual probability of “failure” (i.e. the probability of exceeding the near collapse limit state) of a structure can be derived, which is appropriate for practical applications, provided that predetermined default values for the dispersion measures are available. In the paper, this simplified approach is summarized and applied to the estimation of the “failure” probability of reinforced concrete frame buildings representing both old structures, not designed for earthquake resistance, and new structures designed according to Eurocode 8. The results of the analyses indicate a high probability of the “failure” of buildings which have not been designed for seismic loads. For a building designed according to a modern code, the conservatively determined probability of “failure” is about 30 times less but still significant (about 1% over the lifetime of the structure).
COBISS.SI-ID: 5478241
Knowledge of the structural behaviour of existing masonry requires a multi-level approach, with the proper application of diagnostic and assessment methodologies. Several masonry heritage structures from Slovenia (Pišece Castle, Church of the Carthusian Monastery at Žiče, and a typical stone-masonry house from the Soča Valley region), which differ both from the historical and structural point of view, have been investigated by means of different testing techniques (NDT,MDT and DT), and their seismic resistance numerically analysed by means of SEM and FEM approach. It was concluded that the effectiveness of any particular diagnostic technique for the investigation of masonry structures, and for the planning restoration, depends on numerous factors which were identified. No single test is self-sufficient for the solving of a particular problem, so a combination of different NDT, MDT and DT should be always performed. In the process of assessing the state of a structure, even a simple investigation technique is better than none. The effort will always be repaid - if not already in the planning stage of the restoration and retrofitting actions, then certainly in the execution stage of the revitalization works, on site.
COBISS.SI-ID: 4963681
A simple method for the assessment of sustainability of a residential building is proposed. The method consists of two steps. First, areas that influence sustainability level of the building (e.g. building architecture and design, in-built materials) are identified. For each area, several elements and corresponding indicators are determined, and expressed either in quantitative or qualitative terms. The impact areas and their corresponding elements influence all three aspects of sustainability. In the second step, the indicators are aggregated according to their influence on individual sustainability aspects. Special attention is placed to the determination of weights assigned to the indicators in order to make the assessment method relevant in the local context. The proposed method is applied to a selected sample building. The results obtained show that the completeness and reliability of the input data is crucial for the reliability of the proposed assessment method. The feedback from the potential users shows that the method has a potential for wider future implementation in practice.
COBISS.SI-ID: 4830305
The paper contains a discussion of the inelastic dynamic magnification of seismic shear forces in cantilever walls with rectangular cross-sections. An extensive parametric study was performed in order to determine the reliability of the procedure in Eurocode 8 (EC8). A large number of single cantilever walls which are characteristic for the design practice in Europe and designed to satisfy all the EC8 requirements were analysed. The results obtained with the (modified) code procedures were compared with the results of inelastic response history analyses. If properly applied, the EC8 procedure for DCH walls usually yields good results for the base shears. However, as presently formulated and understood in the EC8, it can yield significantly incorrect results (overestimations of up to 40%). For this reason three modifications were introduced: (1) Keintzel’s formula, which is adopted in EC8, should be used in combination with the seismic shears obtained by considering the first mode of the excitation only; (2) the upper limit of the shear magnification factor should be related to the total shear force; and (3)a variable shear magnification factor along the height of the wall should be applied. The present procedure in EC8 for DCM structures (using a constant shear magnification factor of 1.5 for all walls) is non-conservative.
COBISS.SI-ID: 5503585
Incremental dynamic analysis (IDA) was extended by introducing a set of structural models in addition to the set of ground motion records which is employed in IDA analysis in order to capture record-to-record variability. The set of structural models reflects epistemic uncertainties, and is determined by utilizing the latin hypercube sampling (LHS) method. The effects of both aleatory and epistemic uncertainty on seismic response parameters are therefore considered in extended IDA analysis. It is shown that epistemic uncertainty could significantly reduce the collapse capacity of a structure. The estimated seismic risk is consequently underestimated if the impact of the epistemic uncertainty is neglected.
COBISS.SI-ID: 4362337